This invention relates to a grain bin which is typically used for on-farm grain conditioning and storage purposes. Even more specifically, this invention relates to the construction of a grain bin having a roof vent or other opening in the roof of the grain bin which is specifically constructed so as to avoid rainwater or the like flowing down the slope of the roof of the grain bin from entering the bin.
In recent years, it has become conventional for farmers to condition (i.e., dry) and to store at least a certain portion of their grain crops (e.g., corn, soybeans, rice, or wheat) in on-farm storage bins. Conventionally, on-farm grain storage bins comprise a generally cylindrical-shaped bin made of sheet metal panels which are mounted on a concrete foundation slab. These bins may vary considerably in diameter and height so as to accommodate a wide variety of quantities of grain which may be stored therein. The grain bin typically further includes a conical-shaped roof made of a plurality of sheet metal, wedge-shaped roof panels which slope upwardly and inwardly from the outer upper surface of the cylindrical bin and which are secured together at the upper center of the roof by means of a peak collar. Oftentimes, this peak collar serves as the entry point into which grain is loaded into the bin by means of a grain spreader suspended from the peak collar.
Further, a grain bin which is used to condition (dry) grain often includes a perforated floor raised above the concrete foundation slab such that an air plenum exists under the floor. This plenum is typically in communication with a fan system and a heater for blowing heated air into the plenum. This heated air is then forced up through the perforated floor, through the grain and is exhausted through the peak collar and also through one or more roof vents provided in the roof of the grain bin. Of course, it is necessary that there be sufficient vent area in the bin to allow the heated air carrying the moisture from the grain to readily escape thereby to permit the moisture to be expelled and to prevent the undue buildup of static pressure within the grain bin.
Typically, prior art roof vents were generally of rectangular cross-section and were installed on selected of the roof panels such that the roof vent was in communication with the interior of the grain bin. The roof vent faces generally downwardly away from the peak of the roof so as to prevent rainwater and the like from entering the bin through the exhaust opening. The exhaust opening is covered with a screen so as to prevent birds and other animals from entering the bin.
However, there have been several longstanding problems associated with prior roof vents. One such problem was that it was a relatively difficult matter to effectively seal the roof vent relative to the roof panel on which it was installed so as to prevent rainwater and condensation from running down the outer surface of the sloped conical roof and from entering the grain bin via the opening provided in the roof panel for the roof vent. In certain prior roof vent designs, an opening was field cut in a selected roof panel and the roof vent was bolted to the roof panel adjacent the opening. A mastic-like sealant was used to seal the roof vent to the roof panel.
In other prior art roof vents (see FIGS. 10 and 11), the roof vents had flanges which mated in face-to-face relation with the outer surface of the roof panel and an extension which protruded into a hole field-cut into a selected roof panel by field installation personnel. Caulking material was applied between the roof panel and these flanges. The extensions protruding into bin through the opening are then bent over on the inside of the roof panel so as to sandwich the roof panel between the flange on the bent over extension. Self-tapping metal screws were then inserted through the flange, the roof panel and the bent over extensions.
However, with both of the above-described prior art roof vents, the mastic served as the only seal. Also, due to improper installation of the roof vent such as may be caused by improperly sized or improperly cut openings in the roof panels, due to the tendency of the caulking material to crack over time (which may in part be the result of both the roof panels and the roof vents being of light gauge sheet metal and thus being subject to flexing), these prior art roof vents oftentimes leaked. The requirement of having to field cut the openings in the roof panels oftentimes resulted in oversize and undersize openings which in turn lead to leaking roof vents. Still further, with the advent of longitudinal corrugations in the roof panel, it was difficult for the mastic to effectively seal the roof vent.
As heretofore mentioned, prior roof vents were generally of rectangular cross section. While it was highly advantageous to ship the roof vents in an assembled form so that they may be readily installed on the grain bin in the field, these roof vents were relatively large in size and thus required a substantial shipping container and posed a disadvantage in shipping in that they took up considerable volume while having little weight. Still further, prior pre-assembled roof vents, due to their large size and sheet metal construction, were subject to damage during transport from the factory to the on-farm installation site.